Technical Abstract:
Our research on bacteriophage has demonstrated that bacteriophage can be used to prevent and treat colibacillosis in broiler chickens. A study was conducted to evaluate the therapeutic efficacy of bacteriophage and the antibiotic enrofloxacin individually and in combination to treat colibacillosis. The experimental design was a 2 x 2 x 2 factorial with 8 treatments and 4 replicate pens of 10 birds. The treatments were control, unchallenged birds treated with bacteriophage, enrofloxacin, or the combination; birds challenged with E. coli; and birds challenged with E. coli and treated with either bacteriophage, enrofloxacin, or the combination of bacteriophage and enrofloxacin. When the birds were 7 d of age they were challenged by injecting 10(4) cfu of E. coli into the thoracic air sac. The antibiotic treatment was initiated immediately after the birds were challenged and consisted of 50 ppm enrofloxacin in the drinking water for 7 consecutive days. The bacteriophage treatment consisted of a single intramuscular injection of 2 different bacteriophage 10(9) pfu administered immediately after the E. coli challenge. Mortality in the birds challenged with E. coli and untreated was 68%. The bacteriophage treatment significantly decreased mortality from 68 to 15%. Enrofloxacin significantly decreased mortality from 68 to 3%. There was total protection in birds that received both the bacteriophage and enrofloxacin. The decrease in mortality with enrofloxacin (3%) was significantly better than the decrease in mortality with bacteriophage (15%). Both enrofloxacin and bacteriophage provided effective treatment of colibacillosis, and support the concept that bacteriophage can be an effective alternative to antibiotics. These data also suggest that the combination of bacteriophage treatment with antibiotic treatment may have value.